In general, rock climbing is performed in a manner that a climber, who climbs a rock with his/her body connected to a rope, hooks a karabina on a fixing bolt that is pre-installed on the rock, hooks the rope that ties his/her body on a bina below the karabina, and continues safe climbing to prevent falling of the climber.
Recently, many climbers prefer a climbing system using cams that are fixedly inserted into and then are removed from a well-developed rock crack rather than driving a bolt into a rock to make a hole on the surface of the rock.
A cam structure that is inserted into a crack in a rock is disclosed in Korean Utility Model Application Publication No. 20-0010088 “Cam for rock climbing”.
The cam for rock climbing in the related art is configured so that a wire cable shaft is positioned in the center of the cam, a wire cam for supporting in a cross direction a cam shaft that rotatably supports the cam is fixedly connected to an end portion of the wire cable shaft, and a pulling handle for rotating the cam is movably combined with the wire cable shaft in an axial direction. The pulling handle is arranged to interlock with the cam in a folded posture through a connection member, and the cam is restrained always to take an open posture by an elastic force of a spring.
The cam for rock climbing as described above has the advantage that it enables a climber to perform rock climbing through repetition of processes of inserting cams into a crack in a rock and then removing the inserted cams from the crack. However, the cam for rock climbing also has the problem that the range of the two adjacent cams to be inserted into the rock crack is limited, and thus a climber should carry several kinds of cam sets having different sizes during his/her climbing.
Further, the rotating angle of the two adjacent cams is small, and thus in the case where the rock crack is very wide, cams that can be actually applied and used are restricted.
Further, it is required for a climber to select an appropriate cam to be inserted among several kinds of cams carried by the climber depending on the state of the rock crack, and this causes great inconvenience to the climber.
Further, since the two cams that are inserted into the rock crack have circular circumferences and the holding force of the cam becomes weak due to the weakening of the spring force, the cam that is inserted into the rock crack may move. If the cam further moves toward the inside of the crack due to such movement, it may be inserted into a space inside the crack, and thus may be unable to be withdrawn. On the other hand, if the cam moves toward the outside due to such movement, it may secede from the crack, and thus securing of safety of the climber may fail to cause danger to the climber.
In addition, since the cam has a massive structure, the cam that is used in a wide rock crack may be very heavy and large in weight and size, and thus it may be actually impossible to carry the cam that suits such a wide rock crack. In other words, the cam as described above has the structural drawback that it is unable to be used for a large crack.
Further, carrying of several cams that are limited in weight and size due to the structural characteristics as described above may cause inconvenience to the climber who desires smooth climbing.